Electric motor driven tool for orthopedic impacting

ABSTRACT

An orthopedic impacting tool comprises a motor, a linear motion converter, an air chamber, a compression piston, an impacting element, an anvil element, and a broach adapter. The compression piston may cause the impacting element to apply controlled force on a broach adapter to create a precise opening for subsequently disposing a prosthesis in a patient. The tool allows forward or backward impacting for expanding the size or volume of the opening or for facilitating removal of the broach and tool from the opening. A force adjustment control of the tool allows a user to increase or decrease the impact force. A light source and hand grips improve ease of operation of the tool.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of pending U.S.patent application Ser. No. 12/980,329, filed on Dec. 29, 2010, thedisclosure of which is incorporated by reference.

FIELD

The present disclosure relates to electric tools for impacting inorthopedic applications, and, more particularly, to an electric motordriven tool for orthopedic impacting that is capable of providingcontrolled impacts to a broach, chisel, or other device for creating anopening in an area (in a bone structure, for example) to securelyreceive prosthesis within the area.

In the field of orthopedics, prosthetic devices such as artificialjoints, are often implanted or seated in a patient's body by seating theprosthetic device in a cavity of a bone of the patient. The cavity mustbe created before the prosthesis is seated or implanted, andtraditionally, a physician may remove worn, excess, or diseased bonestructure from the area in which the cavity will be formed, and thendrill and hollow out a cavity along the medullar canal of the bone. Aprosthesis usually includes a stein or other protrusion that serves asthe particular portion of the prosthesis that is inserted into thecavity.

To create such a cavity, a physician may use a broach, which broachconforms to the shape of the stem of the prosthesis. Solutions known inthe art include providing a handle with the broach, which handle thephysician may grasp while hammering the broach into the implant area.Unfortunately, this approach is clumsy and unpredictable as beingsubject to the skill of the particular physician. This approach almostwill always inevitably result in inaccuracies in the location andconfiguration of the cavity. Further, this approach carries with it therisk that the physician will damage bone structure in unintended areas.

Another technique for creating the prosthetic cavity is to drive thebroach pneumatically, that is, by compressed air. This approach isdisadvantageous in that it prevents portability of an impacting tool,for instance, because of the presence of a tethering air line, air beingexhausted from a tool into the sterile operating field and fatigue ofthe physician operating the tool. Further this approach, as exemplifiedin U.S. Pat. No. 5,057,112 does not allow for precise control of theimpact force or frequency and instead functions very much like ajackhammer when actuated. Again, this lack of any measure of precisecontrol makes accurate broaching of the cavity more difficult.

Another disadvantage of tools known in the art is the accumulation offluids, such as body fluids or moisture, on handgrips of such toolsduring prolonged periods of use. For example, difficulty of operation ofa broach impacting device known in the art may increase during asurgical procedure as handgrips may become saturated with bodily fluidsand thus the physician's hold on such a prior art device may becomeimpaired.

Consequently, there exists a need for an impacting tool that overcomesthe various disadvantages in the prior art.

In view of the foregoing disadvantages of the prior art, an electricmotor-driven orthopedic impacting tool configured to include all theadvantages of the prior art, and to overcome the drawbacks inherenttherein is provided. The tool may be used by orthopedic surgeons fororthopedic impacting in for example hips, knees, and shoulders. The toolis capable of holding a broach, chisel, or other device and gentlytapping the broach, chisel or other device into the cavity withcontrolled percussive impacts, resulting in a better fit for theprosthesis or the implant. Further, the control afforded by such anelectrically manipulated broach, chisel, or other device allowsadjustment of the impact settings according to a particular bone type orother profile of a patient. The tool additionally enables proper seatingor removal of the prosthesis or the implant into or out of an implantcavity.

In an embodiment, an electric motor-driven orthopedic impacting toolcomprises a control unit, a housing, a linear motion convener, at leastone reducing gear, an impacting element (also referred to herein as astriker), an air chamber, as compression piston, and a force adjustmentcontrol means (hereinafter referred to as ‘control means’). The tool mayfurther include a motor, an LED, a handle portion with at least onehandgrip for comfortable gripping the tool, a broach adapter, asbattery, a feedback system and a nose-piece for the broach adapter. Atleast some of the various components are preferably contained within thehousing. The tool is capable of applying cyclic impact forces on abroach, chisel, or other device, or an implant and of finely tuningimpact force to a plurality of levels of impact force.

In an embodiment, the tool further comprises a control means, whichmeans includes a force adjustment element, and which element may controlthe impact force and avoid damage caused by uncontrolled impacts.

The tool further comprises an anvil element, which anvil elementincludes both a forward and rearward point of impact and a guide thatconstrains the striker to move in a substantially axial direction. Inoperation, the movement of the striker along the guide of the anvilelement continues in either a forward, or rearward direction until thestriker hits the point of impact. As used in this context, “forwarddirection” connotes movement of the striker toward a broach or patient,and “rearward direction” connotes movement of the striker away from thebroach or chisel or patient. If the impact point is at the front of thetool, i.e., in a forward direction, the impact causes the percussiveforce to be transmitted to a broach or chisel, pushing it further intothe cavity. If the impact point is at the rear of the tool, thepercussive force tends to pull the broach or chisel out of the cavity.The selectivity of either bidirectional or unidirectional impactingprovides flexibility to a surgeon in either cutting or compressingmaterial within the implant cavity, in that the choice of materialremoval or material compaction is often a critical decision in asurgical procedure. The impact point may be in the form of an plate thatis disposed at an end or each end of the anvil element.

The tool is further capable of regulating the frequency of the striker.By regulating the frequency of the striker, the tool may impart agreater total time-weighted percussive impact, while maintaining thesame impact magnitude. This allows for the surgeon to control thecutting speed of the broach or chisel. For example, the surgeon maychoose cutting at a taster rate (higher frequency impacting) during thebulk of the broach or chisel movement and then slow the cutting rate asthe broach or chisel approaches a desired depth.

A user may firmly hold the tool by the handle portion and utilize lightemitted by the LED to light up a work area and accurately position thebroach, chisel, or other device on a desired location on the prosthesisor the implant. The reciprocating movement imparted on broach, chisel,or other device causes tapping of the implant and/or broach, chisel, orother device and thereby enables proper seating or removal of aprosthesis or implant into or out of an implant cavity, or controlledimpacting of a broach, chisel, or other device to create or shape animplant cavity. The tool may also include a feedback system that warnsthe surgeon, when a bending or off-line orientation beyond a certainmagnitude is detected at a broach, chisel, or other device/implantinterface.

These together with other aspects of the present disclosure, along withthe various features of novelty that characterize the presentdisclosure, is pointed out with particularity in the claims annexedhereto and forms a part of this present disclosure. For a betterunderstanding of the present, disclosure, its operating advantages, andthe specific objects attained by its uses, reference should be made tothe accompanying drawing and descriptive matter in which there areillustrated exemplary embodiments of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages and features of the present invention will become betterunderstood with reference to the following detailed, description andclaims taken in conjunction with the accompanying drawings, wherein likeelements are identified with like symbols, and in which:

FIG. 1 shows a perspective view of an orthopedic impacting tool, inaccordance with an exemplary embodiment of the present disclosure;

FIG. 2 shows a perspective view of a compression piston compressing airagainst a striker of an orthopedic impacting tool, in accordance with anexemplary embodiment of the present disclosure;

FIG. 3 shows a striker releasing and striking an anvil element, inaccordance with an exemplary embodiment of the present disclosure;

FIG. 4 shows a compression piston of an orthopedic impacting toolreturning from a forward position and compressing air on the forwardside of a striker, in accordance with an exemplary embodiment of thepresent disclosure;

FIG. 5 shows a striker of an orthopedic impacting tool moving rearward,in accordance with an exemplary embodiment of the present disclosure;and

FIG. 6 shows a striker of an orthopedic impacting tool impacting a rearanvil impact plate, in accordance with an exemplary embodiment of thepresent disclosure.

Like references numerals refer to like parts throughout the descriptionof several views of the drawings.

DETAILED DESCRIPTION OF THE DISCLOSURE

The best mode for carrying out the present disclosure is presented interms of its preferred embodiment, herein depicted in the accompanyingfigures. The preferred embodiments described herein detail forillustrative purposes are subject to many variations. It is understoodthat various omissions and substitutions of equivalents are contemplatedas circumstances may suggest or render expedient, but are intended tocover the application or implementation without departing from thespirit or scope of the present disclosure.

The terms “a” and “an” herein do not denote a limitation of quantity,but rather denote the presence of at least one of the referenced items.

Referring now to FIGS. 1-6, the present disclosure provides an electricmotor-driven orthopedic impacting tool with controlled percussiveimpacts. The tool includes the capability to perform single or multipleimpacts as well as impacting of variable speeds, forces and frequencies.The impact force can be tuned to one of a variety of levels by settingthe impact force electronically.

The tool includes a housing. The housing securely covers and holds aplurality of components of the tool. In an embodiment, the housingcontains a motor, at least one reducing gear, a linear motion converter,a compression chamber, an impacting element (alternately referred to asa striker), a force or impact adjustment control means (hereinafterreferred to as ‘control means’), and an anvil element with a forwardimpact plate and a rearward impact plate (which impact plates may bepart of the anvil, for example).

The tool further may include a handle portion with at least one handgrip for comfortable and secure holding of the tool while in use, abroach adapter, a battery, and a positional sensor, a directionalsensor, and/or a torsion sensor. The tool may further comprise anlighting element such as an LED to provide light in the work area inwhich a user employs the tool. The broach adapter can be coupled to ananvil, of the anvil element for example, through a quick connectmechanism at the end of the tool that is directed at a patient when thetool is in use.

In an embodiment, and referring now to FIG. 1, the linear motionconverter comprises a slider crank mechanism 12, which slider crank isoperatively coupled to the motor 8 and reducing gears 7 and 9. The toolfurther comprises an air chamber 5, 17 that accepts a compression piston6 with a first end and a second end, which compression piston 6 isactuated by the linear motion convener 12. As the compression pistonwill have a smaller longitudinal dimension than the air chamber thatcontains the piston, it will be apparent that an air mass will bepresent at either end of the compression piston while the compressionpiston is within the air chamber. Hereinafter, the air mass disposedbetween the head of compression piston and the striker will be referredto as the “forward air chamber portion,” or “forward air chamber” 5, andthe air mass disposed between the end of the compression piston that isproximate to the linear motion converter and the motor of the tool willbe referred to as the “rear air chamber portion,” or “rear air chamber”17.

In an embodiment of the present disclosure the motor of the tool causesthe linear motion converter to move the compression piston untilsufficient pressure is built within the forward air chamber 5 that isdisposed between the forward end of the compression piston and therearward end of the striker 4 to overcome the inertia and frictionalforce that holds the striker 4 in a position. Once this sufficientpressure is reached, the force of the air pressure accelerates thestriker 4, which striker 4 slides axially down as cavity internal to thetool housing and strikes the forward anvil impact plate 15. Theresultant force is communicated through the anvil 14 that is proximateto the impact plate 15 and, optionally, through the broach adapter 1(which adapter will be described in more detail below) to which abroach, chisel, or other device for seating or removing an implant, orprosthesis may be attached.

As the compression piston 6 continues through its stroke it movestowards the rear direction, compressing the air mass in the rear airchamber 17. This air mass may be communicated through art air passagewayto the front side of the striker 4, creating a returning force on thestriker 4, which returning force causes the striker 4 to move in a reardirection, i.e., a direction away from the point of impact of thestriker the forward anvil impact plate 15. The striker continues to moveuntil it impacts the rear anvil impact plate 16. Striking, the rearimpact plate creates a rear directed force on the anvil 14. In the eventthat a broach adapter 1 is attached to the anvil 14, the force iscommunicated through the broach adapter 1 to which the broach, chisel,or other device fix seating or removing an implant, or prosthesis isattached. Thus in one complete cycle, a forward and rear directedimpacting force can be applied on the broach, chisel, or other device,or implant/prosthesis.

In an embodiment, the compression piston preferably has a cavity on thehead thereof, which cavity creates pressure during the return stroke ofthe piston, which pressure causes the front end of the striker to moveaway from the forward anvil impact plate impact the rearward point ofimpact of the anvil element. It will be apparent that the strikerimpacting the rear anvil impact plate will communicate a negative forceto the front of the anvil (and broach, chisel, or other device), whichnegative force will move the broach, chisel, or other device away fromthe location of impact in a surgical area.

The slider crank embodiment of the tool facilitates controlledcontinuous impacting oldie striker and anvil. For such continuousimpacting, after causing compression by the compression piston, theslider crank returns to the bottom of its stroke, which return releasespressure on the striker and, in the above-described embodiment whereinthe piston comprises a cavity on the head thereof, may pressurize thefront of the striker, causing the striker to return to its initial restposition.

For a single stroke, the linear motion converter (such as the slidercrank described herein) will stop at or near the rear position, thusreleasing the forward pressure on the striker and allowing the strikerto return it to its starting position in readiness for another stroke.In this operational mode, a user may cause the tool to impactselectively (as opposed to repeatedly), thus allowing further control ofthe impacts and the creation or shaping of the surgical area, forexample.

A positional sensor, coupled operatively to the control unit may beprovided to assist in regulating a preferred positional cyclic operationof the linear motion converter. For example, the control unit ma causethe slider crank to come to rest at or near the fully back position inreadiness to generate pressure for the next impact upon receiving asignal from the positional sensor that the slider crank has reached thebottom dead center position. In another embodiment, the control unit maybe directly coupled to the linear motion converter for initiating andceasing operation of the linear motion converter.

The control unit is further capable of operating the force control meansfor selectively tuning the amount of impact force per cycle. Bycontrolling the impact force the tool can avoid damage caused byuncontrolled impacts or impacts of excessive force. For example, a usermay reduce the impact setting in the case of an elderly patent withosteoporosis, or may increase the impact setting for more resilient orintact athletic bone structures.

The control unit may also control the force of impacting by modulatingthe speed of advancing (forward directional travel) and/or the speed ofretraction (rearward directional travel) of the compression piston. Itwill be apparent that the modulation of speed of the compression pistonwill affect the buildup of pressure for forward and rearward directionaltravel of the striker. For example, where the speed of the forwarddirection of the piston is relatively high, and the speed of therearward direction of the piston is relatively low, the velocity of thestriker in the forward direction will be much higher, causing theimparted percussive impact of the striker to be greater in the forwarddirection of the piston and striker. This modulation of the speed of thepiston in the forward and rearward direction allows a user to create agreater impacting force, when so desired (e.g., to create a surgicalarea) or a greater rearward force, to facilitate removing a broach,chisel, or other device from the surgical area, for example. In theinstance where the forward and rear velocities are the same, the toolallows for bidirectional movement of the broach, chisel, or other deviceduring operation, which creates a very efficient technique for machiningthe cavity.

The motor of the tool may be configured to assist particularly with suchmultidirectional impacting. In an embodiment, the motor may operateunder pulse-width modulation for rearward striking and may operate underfull or continuous speed for forward striking of the striker. In suchoperation, the broach, chisel, or other device attached to the tool mayundergo near forward only motion, which operation will facilitate thecreation of an implant seat. Alternatively, the motor may operate underpulse-width modulation for forward striking and may operate under fullor continuous speed for rearward impacting, which operation can createan extraction motion useful for dislodging a broach, chisel, or otherdevice that has become stuck or removing an implant.

In a further embodiment, the tool comprises a positional sensor, such asan anvil positional sensor that may be operatively coupled to thecontrol unit of the striker of the tool. This positional sensor iscapable of determining whether the operator is pushing or pulling on thetool. For instance, the sensor may determine such pushing, or pullingbased upon the position of the broach-holding adapter or anvil. Thisdetermination can have the effect that when a user is exerting force onthe tool in a particular direction the impacting of the striker isaccordingly adjusted. For example, if the sensor determines that theuser is pushing on the tool or is pushing the tool against an object,that sensor can cause the striker to impact in a forward direction. Ifthe sensor determines that the user is pulling on the tool, that sensormay cause the striker to impact in a rearward direction or may cause apulling force to be exerted on the striker by way of the cycling of theslider crank.

The tool may further comprise a lighting element, and, in an embodiment,the lighting element may comprise an LED arrangement, which lightingelement may be capable of illuminating a user's work area. In anembodiment, the LED may be disposed on the housing of the tool and maybe oriented toward a patient's body or surgical cavity.

The tool may further comprise a plate or other flat surface at the endof the tool that is distal to the surgical area, which plate may allow auser to apply selective manual pressure on a broach, chisel or otherdevice, or a surgical implant as dictated by surgical or physicalconditions. For instance, if a broach is firmly lodged within a cavitysuch that the operation of the tool would not remove the broach, theuser may manually tap on the plate to dislodge the broach.

The tool may further comprise a torsion sensor, which torsion sensor maybe capable of determining a lateral or deviating force or movement ofthe tool, such that if the tool is sensed to deviate from apre-determined magnitude at the broach/implant interface, a signal mayemit to notify the user of such deviation. In this manner and otherwise,the tool facilitates consistent axial broaching and implant seating.

In a further embodiment, the broach adapter may comprise a parallel4-bar arrangement. In this embodiment, the adapter may receive a broachfor anterior or posterior joint replacement. The parallel 4-barmechanism of the adapter may facilitate receiving and orienting thebroach in a variety of positions, such as in a centered position, or inan offset left or right position. The adapter will maintain the broachin an orientation that is parallel or co-linear to the body of the tooland the striker. The broach adapter may also comprise clamps, a vice, orany other fastener that may securely hold the broach, chisel, or otherdevice, during operation of the tool.

The tool may further comprise handgrips disposed on the housing of thetool, which handgrips may include a rubberized or other tacky coatingremovably disposed thereon. Such coating facilitates comfortableoperation of the tool and improves the user's hold on the tool forincreased control thereof and reduced fatigue during operation of thetool.

In use, a user such as a surgeon firmly holds the tool by the handlegrip or grips and utilizes light emitted by the LED to illuminate a workarea and accurately position a broach, chisel or other device that hasbeen attached to the tool on a desired location on the prosthesis orimplant. The reciprocating movement imparted by the tool upon thebroach, chisel or other device causes tapping of the implant and therebyenables proper seating, or removal of the prosthesis or the implant intoor out of an implant cavity. The warning system may alert the user inthe event that a bending moment above a certain magnitude is detected ata broach (or chisel or other device)/implant interface.

The tool disclosed herein provides various advantages over the priorart. It facilitates controlled impacting, at a surgical site, whichminimizes unnecessary damage to a patient's body and which allowsprecise shaping of a implant or prosthesis seat. The tool also allowsthe user to modulate the direction and force of impacts, which improvesthe user's ability to manipulate the tool. The force control adjustmentof the impact settings allows a user to set the force of impactaccording to a particular bone type or other profile of a patient. Thetool thereby enables proper seating or removal of the prosthesis or theimplant into or out of an implant cavity.

The foregoing descriptions of specific embodiments of the presentdisclosure have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit thepresent disclosure to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The exemplary embodiment was chosen and described in order tobest explain the principles of the present disclosure and its practicalapplication, to thereby enable others skilled in the art to best utilizethe disclosure and various embodiments with various modifications as aresuited to the particular use contemplated.

What is claimed is:
 1. An orthopedic impacting tool for striking anobject, the tool comprising a motor, a linear motion converter, acompression piston operatively coupled to said linear motion converter,said piston having a first end and a second end, an air chamber, saidair chamber comprising a forward portion and a rear portion, whereinsaid forward portion is proximate to said first end of said compressionpiston and said rear portion is proximate to said second end of saidcompression piston, an impacting element, a control unit, an anvilelement with a front face and a rear face, said anvil element adapted toaccept a portion of a broach adapter, a broach adapter capable ofholding a broach, chisel, reamer, or other surgical implement, saidbroach adapter operatively coupled to said anvil element and beingproximate to said first face of the anvil element and distal to saidsecond face of said anvil element, and a hand grip, wherein said controlunit directs said motor to move said linear motion converter and causingsaid compression piston to move and compress air within said frontportion of said air chamber or compress air within a second portion ofsaid air chamber, and wherein said impacting element moves to impactsaid front face of said anvil element, upon application of compressed anfrom the first portion of said air chamber and wherein said impactingelement moves to impact said rear face of said element upon applicationof compressed in from the second portion of said air chamber such thatthe impacting element is capable of imparting a force upon the broachadapter in at least one direction.
 2. The tool of claim 1, wherein saidlinear motion converter comprises a slider crank mechanism.
 3. The toolof claim 1, wherein said linear motion converter and motor comprise avoice coil motor.
 4. The tool of claim 1, wherein the control unitallows for single percussive impacting.
 5. The tool of claim 1, whereinsaid tool further comprises a lighting element disposed on an exteriorsurface of the tool, said lighting element operatively coupled to thecontrol unit.
 6. The tool of claim 1, wherein the velocity of saidimpacting element is controlled by the speed at which the air iscompressed or decompressed.
 7. The tool of claim 1, wherein the toolcomprises a positional sensor that is operatively coupled to one of thecontrol unit of the tool or the motor of the tool, which sensor maydetermine whether the tool is being pushed toward an object or pulledaway from an object, which sensor causes said control unit or motor ofthe tool to direct the impacting element to impart a greater force uponsaid front face of said anvil element and a lesser force on said rearface of said anvil element upon sensing that the tool is being pushedtoward an object, and which sensor causes said control unit or motor ofthe tool to direct the impacting element to impart a lesser force uponsaid front face of said anvil element and a greater force on said rearface of said anvil element upon sensing that the tool is being pulledaway from an object.
 8. The tool of claim 1, wherein said tool comprisesa torsion sensor, which torsion sensor is capable of determining alateral movement of the tool and which sensor is capable of signalingsuch movement.
 9. The tool of claim 1, wherein said broach adapter hasan adjustment to offset an attached broach, chisel, reamer, or othersurgical implement from the central axis of the tool while maintaining aparallel orientation of the broach, chisel reamer, or other surgicalimplement with respect to the central axis of the tool.
 10. The tool ofclaim 1, wherein said broach adapter comprises a parallel four-barmechanism.